If the point of the references [1]}, [2]}, [3]} is right, there isn't quantum entanglement between A and B systems and A and C systems. But this conclusion contradicts a logical fact: if A gets entangled with BC system group, A must get entangled with at least one of B and C systems, otherwise A will get not entangled with BC system group. It is a logical fact that speaks for itself. Obviously only accepting the point that Eq.(1) contains quantum entanglement can resolve this question.
